Hi, anyone had a problem with their heater not blowing hot air? Any help is greatly appreciated.

Mine won't blow hot or cold. I'm thinking I need to replace the heater core, but I just posted something hoping for other suggestions.

What I've checked so far are the hoses and the hot / cold selection valve. Both are located in the top of the engine compartment coming out of the firewall on the passenger side. Make sure coolant is going through the two hoses (one into the core and one coming out) that go into the firewall. You can test that by letting the engine run for a little with the heater on and touching the hoses to see if their hot. Also, there's a valve right there connected to the top hose that should move when switching your climate control from cold to hot and vice-versa. If both are working correctly, you probably have a bad heater core.

I'm definitely a novice though, so I would take that information and run it by someone with more experience first.

I have the same problem with mine.

I had a similar problem when I changed out my radiator and what happened was I had developed an air bubble in the upper heater hose. what I did to get the air out is while the engine is running and the thermostat is open and engine up to temp squeeze that upper hose to force out the air pocket and try and suck in some coolant. that seemed to work also try to run the heater as hot as it will go and rev up the engine, this seemed to help push the bubble through the system and back to the radiator.

these ideas worked for my vette, hope that it helps with yours.

Greg

gstjohn,

by "uppter heater hose," do you mean the top one coming out of the firewall? I might need to try this.

Im not sure if it is the upper one coming out of the firewall but I do know that it is the hose that goes to the intake manifold and is higher than the thermostat housing. without having the hood open on my vette I cannot remember if it is the upper hose from the firewall. I will try and look tonight and give you a definate answer tonight or tomorrow.

Greg

I know what you're talking about now. I was way off. I'm going to check that out (might as well check them all). Thanks again.

okay then, hope that this fixes your problem.

Greg

I have a 94 C4, had the water pump replaced and since that was replaced, I too have no heat, what can I check as the dealer says I was using the wrong setting.....NOT......I have tried all buttons and NO HEAT at all...Help!:(

i bought my 94 c4 without heat and i took it to pep boys (i know, shame on me...) and they wanted to charge me 800 bucks to take off the dash and tell me what was wrong with it. they said it would be around 7 our 8 hours worth of work. I took it to a friend at church and he took my dash off in 30 minutes, looked behind all the wires and computers on the passenger side and it was a part that i believe was called a Vent Door Actuator. it was a 35 or 40 dollar part that all it does it changes the air from hot to cold and the hotter you want it, it allows more heat, the colder is the opposite. The piece had siezed up and it was a very easy fix and i got away only payin about 200 bucks to fix it when pep boys wanted 800 to tell me what was wrong. good luck and i hope i helped.

just a question, but did that advice help at all. my reason for wanting to know is just to see if it is a frequent problem with c4's. if so, ill be sure never to buy one again haha...

the problem most of you are all referring to is more than likely the vent dorr actuator as mentioned above, while the cooling system may need to be burped id put the smart money on the actuator. its not a common problem on just vettes, many cars are palgued by this. a compan near my old town called rad air basically survibes by charging people insane amounts of money for "dash removal labor" and swapping out that relatively affordable part. dash disassembly is relatively easy and anyone with some mechanical experience should be fully capable of removing it. as with any disassembly, keep track of screws, parts and what order they were removed in to aid reassembly